Process control systems commonly employ pressure regulators (e.g., back-pressure regulators) to control or maintain the pressure of a pressurized fluid such as, for example, air, hydraulic fluid, etc. at or below a certain pressure. Maintaining or controlling a pressure of the process fluid may serve to protect instruments or other control devices that are sensitive to and which may be damaged by high pressures. For example, a back-pressure fluid regulator typically regulates a pressure of a high pressure fluid source to prevent high pressure fluid from reaching instruments or control devices upstream from the back-pressure regulator. A back-pressure regulator is typically configured to relieve or reduce excess fluid pressure when a pressure of a pressurized fluid increases to a pressure greater than a desired operating pressure suitable for use by the various instruments or control devices receiving the pressurized fluid.
Fluid regulators such as, for example, back-pressure regulators typically include a fluid valve assembly having a pressure sensor such as a piston to sense the pressure of a pressurized fluid at an inlet of the regulator. When the pressure of the pressurized fluid at the inlet exceeds a reference or set-point pressure (e.g., provided by the fluid regulator), the pressure sensor causes a flow control member of the fluid valve to open to allow fluid flow through the regulator body between the inlet and an outlet, which may be coupled to a low pressure system utilizing the fluid or to the atmosphere.
However, back-pressure regulators employed in high pressure fluid systems are often subjected to a relatively high pressure differential across the regulator (e.g., between an inlet and an outlet). In particular, when used in high pressure hydraulic applications, the valve assembly of a back-pressure fluid regulator may be subjected to a pressure differential of, for example, 10,000 psi. Such a high pressure differential results in high fluid flow rates across the fluid valve assembly, thereby causing components such as a valve plug, a valve seat, etc. of the fluid valve assembly to become damaged due to, for example, erosion. Undesired leakage may occur as a result of such erosion, thereby reducing the useful life of the back-pressure regulator, increasing maintenance, system downtimes, and/or costs.